Baclayon Ancient Marine Terrace

The uplifted marine terraces in Baclayon are a similar landform to the more recently uplifted marine terrace in Maribojoc. However, the terraces in Baclayon are much older. It was formed during the Pliocene-Pleistocene time (5 million years – 11,000 years ago). Fault movement along the coast caused the uplift of formerly underwater reefs raising it at a height above the sea and creating a marine terrace along the coast. Several other subsequent fault movements shaped the successive step-like characteristic of the marine terraces seen at Baclayon. The three-step terraces there stand at 20 meters, 40 meters and 60 meters above sea level signifying at least three episodes of progressive tectonic uplift in the area. The ancient marine terraces can be observed in the step-like quality of uphill roads that branches inland from the highway in Baclayon.

Fragments of large and thick shells (Tridacna gigas) and fragments of the gastropod group Strombaceae, have been collected in the area. Two terraces in Baclayon were tested using the Uranium-Thorium Analysis to identify the age and determine when the terraces were uplifted. The results point to an age of around 129,000 years old for the terrace with an altitude of 20 m, and approximately 310,000 years old for the terrace with an altitude of 60 m.